Systems and methods for distribution of digital content to end-users are well known. In one such system, identical copies of digital content are distributed by a content server via a computer network, such as the Internet, to one or more proxy servers. An end-user requesting digital content from the content server may then be redirected to a proxy server that is nearer to the end-user than is the content server. The proxy server then distributes the digital content to the end-user more quickly and efficiently than would the content server, as the content has less far to travel.
Methods for anti-piracy protection of digital content are also well known. In one such method, a digital watermark that is uniquely associated with a particular end-user is embedded into the digital content at the content server prior to distribution to the end-user. The network is then monitored for unauthorized redistribution of the digital content to other end-users not associated with the digital watermark.
While it would be advantageous to combine methods of efficient distribution of digital content with anti-piracy methods that employ digital watermarking, current proxy server-based distribution methods require that all copies of digital content stored on proxy servers be identical, while digital watermarking methods often require that unique variants of the original content be created. Clearly, the storage of each variant on every proxy server would be inefficient and impractical, if not impossible.
Some prior art systems attempt to solve this problem by distributing identical copies of digital content to proxy servers and end-users, and embedding the digital watermark into the digital content at the end-user's receiving apparatus. However, this approach does not provide an adequate level of security as the receiving apparatus may be tampered with and, therefore, cannot be trusted to perform the embedding of the watermark.
The following U.S. Patents are believed to be representative of the current state of the art of digital watermarking techniques: U.S. Pat. Nos. 5,809,139, 5,915,027, 5,960,081, 6,069,914, and 6,131,161.
The disclosures of all patents, patent applications, and other publications mentioned in this specification and of the patents, patent applications, and other publications cited therein are hereby incorporated by reference.